Title page for ETD etd-07092004-112341

Type of Document

Thesis

Author

Xu, Bin

URN

etd-07092004-112341

Title

Study of the Magnetic Field Dependence of the Critical Current of Bi2sr2cacu2o8+X and (Bi,Pb)2sr2ca2cu3o10+X Superconducting Tapes

Degree

Master of Science

Department

Mechanical Engineering, Department of

Advisory Committee

Advisor Name	Title
Cesar Luongo	Committee Member
Justin Schwartz	Committee Member
Simone Peterson Hruda	Committee Member

Keywords

Angular Distribution
Hysteresis
Bi-2223
Bi-2212
Magnetic Field Dependence

Date of Defense

2004-06-28

Availability

unrestricted

Abstract

The magnetic field dependence of critical currents are studied in Bi2Sr2CaCu2O8+x and (Bi,Pb)2Sr2Ca2Cu3O10+x multifilamentary superconducting tapes. The critical current was measured in the magnetic fields up to 5 T, at 4.2 K, with several orientations of the applied magnetic field relative to the tape.
The critical current is determined by the normal (c-axis) component of the applied magnetic field over a wide range. At low magnetic fields, the field dependence of the critical current is mainly dominated by weak-links, while at the higher fields it is determined by the strong-links current path limited by intragranular flux pinning.
Two-dimensional behavior of the critical current in Bi2Sr2CaCu2O8+x and (Bi,Pb)2Sr2Ca2Cu3O10+x multifilamentary tapes is observed. From 2D behavior it is possible to calculate the average misalignment angle of the grains from critical current measurements in a magnetic field oriented perpendicular and parallel to the tape plane.
The results are compared with a reported model that describes the angular dependence of critical currents [*]. The model is based on a Gaussian distribution of the misalignment angles of the grains. With this model it is possible to calculate the standard deviation of the misalignment angle of the grains from critical current measurements in a magnetic field oriented perpendicular and parallel to the tape plane. This model is confirmed experimentally. The angular dependence of the critical current of the measured tapes can be described at 4.2 K in the region between 0 and 5 T by using a standard deviation.

[*] O. van der Meer, B. ten Haken, and H.H.J. ten Kate, "A model to describe the angular dependence of the critical current in a Bi-2223/Ag superconducting tape," Physica C 357-360, 1174 (2001).

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